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An interlude of dark exposure for about 1 week is known to shift excitatory/inhibitory (E/I) balance of the mammalian visual cortex, promoting plasticity and accelerating visual recovery in animals that have experienced cortical lesions during development. However, the translational impact of our understanding of dark exposure from animal studies to humans remains elusive. Here, we used magnetic resonance spectroscopy as a probe for E/I balance in the primary visual cortex (V1) to determine the effect of 60 min of dark exposure, and measured binocular combination as a behavioural assay to assess visual plasticity in 14 normally sighted human adults. To induce neuroplastic changes in the observers, we introduced 60 min of monocular deprivation, which is known to temporarily shift sensory eye balance in favour of the previously deprived eye. We report that prior dark exposure for 60 min strengthens local excitability in V1 and boosts visual plasticity in normal adults. However, we show that it does not promote plasticity in amblyopic adults. Nevertheless, our findings are surprising, given the fact that the interlude is very brief. Interestingly, we find that the increased concentration of the excitatory neurotransmitter is not strongly correlated with the enhanced functional plasticity. Instead, the absolute degree of change in its concentration is related to the boost, suggesting that the dichotomy of cortical excitation and inhibition might not explain the physiological basis of plasticity in humans. We present the first evidence that an environmental manipulation that shifts cortical E/I balance can also act as a metaplastic facilitator for visual plasticity in humans. KEY POINTS: A brief interlude (60 min) of dark exposure increased the local concentration of glutamine/glutamate but not that of GABA in the visual cortex of adult humans. After dark exposure, the degree of the shift in sensory eye dominance in favour of the previously deprived eye from short-term monocular deprivation was larger than that from only monocular deprivation. The neurochemical and behavioural measures were associated: the magnitude of the shift in the concentration of glutamine/glutamate was correlated with the boost in perceptual plasticity after dark exposure. Surprisingly, the increase in the concentration of glutamine/glutamate was not correlated with the perceptual boost after dark exposure, suggesting that the physiological mechanism of how E/I balance regulates plasticity is not deterministic. In other words, an increased excitation did not unilaterally promote plasticity.
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Glutamina , Córtex Visual , Animais , Humanos , Adulto , Córtex Visual/fisiologia , Dominância Ocular , Plasticidade Neuronal/fisiologia , Privação Sensorial/fisiologia , MamíferosRESUMO
Multi-view multi-label learning (MVML) is an important paradigm in machine learning, where each instance is represented by several heterogeneous views and associated with a set of class labels. However, label incompleteness and the ignorance of both the relationships among views and the correlations among labels will cause performance degradation in MVML algorithms. Accordingly, a novel method, label recovery and label correlation co-learning for M ulti-V iew M ulti-L abel classification with inco M plete L abels (MV2ML), is proposed in this paper. First, a label correlation-guided binary classifier kernel-based is constructed for each label. Then, we adopt the multi-kernel fusion method to effectively fuse the multi-view data by utilizing the individual and complementary information among multiple views and distinguishing the contribution difference of each view. Finally, we propose a collaborative learning strategy that considers the exploitation of asymmetric label correlations, the fusion of multi-view data, the recovery of incomplete label matrix and the construction of the classification model simultaneously. In such a way, the recovery of incomplete label matrix and the learning of label correlations interact and boost each other to guide the training of classifiers. Extensive experimental results demonstrate that MV2ML achieves highly competitive classification performance against state-of-the-art approaches on various real-world multi-view multi-label datasets in terms of six evaluation criteria.
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Face identity is represented at a high level of the visual hierarchy. Whether the human brain can process facial identity information in the absence of visual awareness remains unclear. In this study, we investigated potential face identity representation through face-identity adaptation with the adapting faces interocularly suppressed by Continuous Flash Suppression (CFS) noise, a modified binocular rivalry paradigm. The strength of interocular suppression was manipulated by varying the contrast of CFS noise. While obeservers reported the face images subjectively unperceived and the face identity objectively unrecognizable, a significant face identity aftereffect was observed under low but not high contrast CFS noise. In addition, the identity of face images under shallow interocular suppression can be decoded from multi-voxel patterns in the right fusiform face area (FFA) obtained with high-resolution 7T fMRI. Thus the comined evidence from visual adaptation and 7T fMRI suggest that face identity can be represented in the human brain without explicit perceptual recognition. The processing of interocularly suppressed faces could occur at different levels depending on how "deep" the information is suppressed.
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Encéfalo/diagnóstico por imagem , Reconhecimento Facial/fisiologia , Imageamento por Ressonância Magnética/métodos , Adaptação Fisiológica , Adolescente , Adulto , Cognição , Estado de Consciência , Feminino , Humanos , Masculino , Reconhecimento Psicológico , Adulto JovemRESUMO
In the recent decade, studies have shown that short-term monocular deprivation strengthens the deprived eye's contribution to binocular vision. However, the magnitude of the change in eye dominance after monocular deprivation (i.e., the patching effect) has been found to be different between different methods and within the same method. There are three possible explanations for the discrepancy. First, the mechanisms underlying the patching effect that are probed by different measurement tasks might exist at different neural sites. Second, the test-retest variability of the same test can produce inconsistent results. Third, the magnitude of the patching effect itself within the same observer can vary across separate days or experimental sessions. To explore these possibilities, we assessed the test-retest reliability of the three most commonly used tasks (binocular rivalry, binocular combination, and dichoptic masking) and the repeatability of the shift in eye dominance after short-term monocular deprivation for each of the task. Two variations for binocular phase combination were used, at one and many contrasts of the stimuli. Also, two variations for dichoptic masking were employed; the orientation of the mask grating was either horizontal or vertical. Thus, five different tasks were evaluated. We hoped to resolve some of the inconsistencies reported in the literature concerning this form of visual plasticity. In this study, we also aimed to recommend a measurement method that would allow us to better understand its physiological basis and the underpinning of visual disorders.
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Dominância Ocular , Visão Monocular , Humanos , Plasticidade Neuronal , Reprodutibilidade dos Testes , Privação Sensorial , Visão BinocularRESUMO
Recent laboratory findings suggest that short-term patching of the amblyopic eye (i.e., inverse occlusion) results in a larger and more sustained improvement in the binocular balance compared with normal controls. In this study, we investigate the cumulative effects of the short-term inverse occlusion in adults and old children with amblyopia. This is a prospective cohort study of 18 amblyopes (10-35 years old; 2 with strabismus) who have been subjected to 2 hours/day of inverse occlusion for 2 months. Patients who required refractive correction or whose refractive correction needed updating were given a 2-month period of refractive adaptation. The primary outcome measure was the binocular balance which was measured using a phase combination task; the secondary outcome measures were the best-corrected visual acuity which was measured with a Tumbling E acuity chart and converted to logMAR units and the stereoacuity which was measured with the Random-dot preschool stereogram test. The average binocular gain was 0.11 in terms of the effective contrast ratio (z = -2.344, p = 0.019, 2-tailed related samples Wilcoxon Signed Rank Test). The average acuity gain was 0.13 logMAR equivalent (t(17) = 4.76, p < 0.001, 2-tailed paired samples t-test). The average stereoacuity gain was 339 arc seconds (z = -2.533, p = 0.011). Based on more recent research concerning adult ocular dominance plasticity, we conclude that inverse occlusion in adults and old children with amblyopia does produce long-term gains to binocular balance and that acuity and stereopsis can improve in some subjects.
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Ambliopia/terapia , Privação Sensorial , Visão Binocular , Adolescente , Adulto , Criança , Feminino , Humanos , Masculino , Estudos Prospectivos , Resultado do Tratamento , Testes Visuais , Acuidade Visual , Percepção Visual , Adulto JovemRESUMO
Matrine is contained in several herbs used in traditional Chinese medicine, named Sophora alopecuroides, Sophora flavescens or Sophora subprostrata. In vitro and in vivo studies have focused on the treatment of chronic hepatitis or liver fibrosis using matrine. However, little is known about its liver pharmacokinetic profile. In this study pharmacokinetics of matrine in rat organs and tissues, such as liver, blood and skin were studied after intravenous (40 mg/kg) or transdermal administration (6 mg/cm2, 5 cm2). Samples were collected at timed intervals for measurement of matrine by a HPLC-UV method. The pharmacokinetic parameters were calculated by non-compartmental analysis using DAS 2.0. The AUC(0-t) values in the liver, blood microdialysates and plasma after intravenous administration were 395.91±74.48, 848.86±146.35 and 1304.07±305.92 min·mg/l, respectively. Following transdermal administration, the AUC(0-t) value in the liver, blood, plasma and skin microdialysates were 695.30±233.79, 1096.07±390.71, 2767.57±518.48 and 42735.77±27938.33 min·mg/l, respectively. Here, we show a promising delivery system for matrine that could replace traditional administration, and a better understanding of the transdermal pharmacokinetics of matrine, which may be helpful for further clinical and laboratory studies.
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Alcaloides/farmacocinética , Cromatografia Líquida de Alta Pressão/métodos , Sistemas de Liberação de Medicamentos , Fígado/metabolismo , Quinolizinas/farmacocinética , Administração Cutânea , Administração Intravenosa , Alcaloides/administração & dosagem , Animais , Área Sob a Curva , Masculino , Medicina Tradicional Chinesa , Microdiálise , Quinolizinas/administração & dosagem , Ratos , Ratos Sprague-Dawley , Distribuição Tecidual , MatrinasRESUMO
In this paper, we describe a simple method for constructing a micellar supramolecular hydrogel, composed of a low-molecular-weight methoxy poly(ethylene glycol) (Mn = 2000 Da) block polymer and α-cyclodextrin (α-CD), for topical ocular drug delivery. Adding aqueous block polymer micelles into an α-CD aqueous solution resulted in the formation of a micellar supramolecular hydrogel through host-guest inclusion. The effects of the drug payload, block polymer, and α-CD concentrations as well as the block polymer structure on gelation time were investigated. The resultant micellar supramolecular hydrogels were thoroughly characterized by X-ray diffraction, rheological studies, and scanning electron microscopy. The hydrogels exhibited thixotropic properties, which are beneficial to ocular drug delivery. In vitro release studies indicated that the α-CD concentration strongly influenced the release rate of diclofenac (DIC) from supramolecular hydrogel. The hydrogels showed relatively low cytotoxicity toward L-929 and HCEC cells and did not significantly affect the migration of the latter after 24 h incubation. The hydrogel was nonirritant toward the rabbit eye, as indicated by the Draize test, fluorescein staining, and histological observation. Nile Red-labeled micellar supramolecular hydrogel showed that it could significantly extend the retention time on the corneal surface in rabbits, compared with a plain micellar formulation. In vivo pharmacokinetics indicated that the hydrogel could greatly improve ocular drug bioavailability, compared with that of micellar formulation. Our results suggest that the micellar supramolecular hydrogel is a promising system for ocular drug delivery.
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Administração Oftálmica , Liberação Controlada de Fármacos , Hidrogéis/efeitos adversos , Micelas , Animais , Anti-Inflamatórios não Esteroides/administração & dosagem , Anti-Inflamatórios não Esteroides/farmacocinética , Linhagem Celular , Diclofenaco/administração & dosagem , Diclofenaco/farmacocinética , Humanos , Hidrogéis/química , Masculino , Camundongos , Polietilenoglicóis/química , Coelhos , Distribuição TecidualRESUMO
Most of the existing 3D talking face synthesis methods suffer from the lack of detailed facial expressions and realistic head poses, resulting in unsatisfactory experiences for users. In this paper, we propose a novel pose-aware 3D talking face synthesis method with a novel geometry-guided audio-vertices attention. To capture more detailed expression, such as the subtle nuances of mouth shape and eye movement, we propose to build hierarchical audio features including a global attribute feature and a series of vertex-wise local latent movement features. Then, in order to fully exploit the topology of facial models, we further propose a novel geometry-guided audio-vertices attention module to predict the displacement of each vertex by using vertex connectivity relations to take full advantage of the corresponding hierarchical audio features. Finally, to accomplish pose-aware animation, we expand the existing database with an additional pose attribute, and a novel pose estimation module is proposed by paying attention to the whole head model. Numerical experiments demonstrate the effectiveness of the proposed method on realistic expression and head movements against state-of-the-art methods.
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The adult human visual system maintains the ability to be altered by sensory deprivation. What has not been considered is whether the internal neural states modulate visual sensitivity to short-term monocular deprivation. In this study we manipulated the internal neural state and reported changes in intrinsic neural oscillations with a patched eye open or closed. We investigated the influence of eye open/eye closure on the unpatched eye's contrast sensitivity and ocular dominance (OD) shifts induced by short-term monocular deprivation. The results demonstrate that internal neural states influence not only baseline contrast sensitivity but also the extent to which the adult visual system can undergo changes in ocular dominance.
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Plasticidade Neuronal , Visão Monocular , Humanos , Adulto , Privação Sensorial , Sensibilidades de Contraste , Dominância Ocular , Visão BinocularRESUMO
OBJECTIVES: To investigate the reliability and validity of Chinese version of the Pediatric Eye Questionnaire (PedEyeQ-CN) by testing ophthalmic patients in China. METHODS: The PedEyeQ (standard English version) was translated by local researchers. Children were asked to complete the Child section, and their parents the Proxy and Parent sections. 160 children (32 normal controls, 77 with refractive error, 48 with strabismus/amblyopia, 3 with other eye conditions) aged 5-11 years old, and one parent of each child were recruited. Cronbach's α and intraclass correlation coefficient were calculated to examine the reliability and test-retest reliability; the score differences between controls and patients were compared to examine the validity. RESULTS: The internal consistency (Cronbach's α ≥ 0.76) and test-retest reliability (r > 0.80) of PedEyeQ-CN were robust. Children with eye conditions had lower scores compared with children with normal vision (refractive error: 10 out of 13 domains, P ≤ 0.021; strabismus/amblyopia: all domains, P ≤ 0.015). Children with strabismus/amblyopia had lower scores compared with children with refractive error (two domains, P = 0.048, P = 0.001). Visual acuity was significantly correlated with functional vision (P = 0.005), but not significantly correlated with the eye-related quality of life (ER-QOL). CONCLUSIONS: The PedEyeQ-CN is a valuable tool for assessing the functional vision and ER-QOL of Chinese children and help us increase our understanding about the impact of eye conditions on children and their families.
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Ambliopia , Erros de Refração , Estrabismo , Humanos , Criança , Pré-Escolar , Qualidade de Vida , Reprodutibilidade dos Testes , Inquéritos e Questionários , Erros de Refração/diagnóstico , Estrabismo/diagnósticoRESUMO
BACKGROUND: Studies have shown that short-term monocular deprivation induces a shift in sensory eye dominance in favor of the deprived eye. Yet, how short-term monocular deprivation modulates sensory eye dominance across spatial frequency is not clear. To address this issue, we conducted a study to investigate the dependence of short-term monocular deprivation effect on test spatial frequency. METHODS: Ten healthy young adults (age: 24.7 ± 1.7 years, four males) with normal vision participated. We deprived their dominant eye with a translucent patch for 2.5 h. The interocular contrast ratio (dominant eye/non-dominant eye, i.e., the balance point [BP]), which indicates the contribution that the two eyes make to binocular combination, was measured using a binocular orientation combination task. We assessed if BPs at 0.5, 4 or 6 cycles/degree (c/d) change as a result of monocular deprivation. Different test spatial frequency conditions were conducted on three separate days in a random fashion. RESULTS: We compared the BPs at 0.5, 4 and 6 c/d before and after monocular deprivation. The BPs were found to be significantly affected by deprivation, where sensory eye dominance shift to the deprived eye (F1.86, 16.76 = 33.09, P < 0.001). The changes of BP were consistent at 0.5, 4, and 6 c/d spatial frequencies (F2,18 = 0.15, P = 0.57). CONCLUSION: The sensory eye dominance plasticity induced by short-term deprivation is not dependent on test spatial frequency, suggesting it could provide a practical solution for amblyopic therapy that was concerned with the binocular outcome.
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Purpose: To investigate the severity and causes of gender imbalance in the counts of ophthalmology citations. Methods: The PubMed database was searched to identify cited papers that were published in four journals (Prog Retin Eye Res, Ophthalmology, JAMA Ophthalmol, and Invest Ophthalmol Vis Sci) between August 2015 and July 2020, and those that referenced these cited papers by 2021 July (i.e., citing papers). The gender category of a given paper is defined by the gender of the first and last author (MM, FM, MF, and FF; M means male and F means female). A generalized additive model to predict the expected proportion was fitted. The difference between the observed proportion and expected proportion of citations of a paper's gender category was the primary outcome. Results: The proportion of female-led (MF and FF) papers slightly increased from 27% in 2015 to 30% in 2020. MM, FM, MF, and FF papers were cited as -9.3, -1.5, 13.0, and 23.9% more than expected, respectively. MM papers cited 13.9% more male-led (MM and FM) papers than female-led papers, and FF papers cited 33.5% fewer male-led papers than female-led papers. The difference between the observed proportion and expected proportion of MM citing papers within male-led and female-led cited papers grew at a rate of 0.13 and 0.67% per year. Conclusion: The high frequency of citations of female-led papers might narrow the gender gap in the citation count within ophthalmology. These findings show that papers by female-led are less common, so the gender gap might still exist even with their high citation count.
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INTRODUCTION: Recent studies indicate that short-term monocular deprivation increases the deprived eye's contribution to binocular fusion in both adults with normal vision and amblyopia. In this study, we investigated whether the changes in visual plasticity depended on the duration of deprivation in normal and amblyopic adults. METHODS: Twelve anisometropia amblyopic observers (aged 24.8 ± 2.3 years) and 12 age-matched normal observers (aged 23.9 ± 1.2 years) participated in the study. The non-dominant eye of normal observers or amblyopic eye of amblyopic observers was deprived for 30, 120, and 300 min in a randomized order. Their eye balance was measured with a phase combination task, which is a psychophysical test, before and after the deprivation. This design enabled us to measure changes induced in binocular balance as an index visual plasticity due to monocular deprivations. RESULTS: By comparing the ocular dominance changes as a result of monocular deprivation with different deprivation durations, we found evidence that the ocular dominance changes are slightly larger after longer deprivations in both normal and amblyopic observers, albeit with a statistical significance. The changes from 120-min were significantly greater than those from 30-min deprivation in both groups. The magnitude of changes in sensory eye balance was significantly larger in normal observers than that in the amblyopic observers; however, the longevity of changes in visual plasticity was found to be more long-lasting in amblyopic observers than the normal counterparts. CONCLUSIONS: The duration of deprivation matters in both normal and amblyopic observers. Ocular dominance imbalance that is typically observed in amblyopia can be more ameliorated with a longer duration of deprivation.
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Amblyopia is a visual disorder that originates from the brain. It exhibits no pathology in the eye. Studies have shown that measuring both visual acuity and binocular balance for assessing amblyopia could be more helpful. However, tests that measure binocular balance are time-consuming, often exceeding 30 min. Their long test durations prevent them from being used in the clinic. For this reason, we have developed a quick (i.e., about 7 min) and precise tool that quantitatively measures binocular balance of patients with amblyopia. The new test can capture binocular imbalance that is typically exhibited at high spatial frequency in amblyopes. In addition, it has an excellent test-retest reliability and repeatability between two experimental sessions. We hope that our newly developed test can pave the road for physicians and researchers to better assess and diagnose amblyopia and other visual disorders that disrupt binocular balance beyond the laboratory.
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Purpose: We developed a stereo task that is based on a motion direction discrimination to examine the role that depth can play in disambiguating motion direction. Methods: In this study, we quantified normal adults' static and dynamic (i.e., laterally moving) stereoscopic performance using a psychophysical task, where we dichoptically presented randomly arranged, limited lifetime Gabor elements at two depth planes (one plane was at the fixation plane and the other at an uncrossed disparity relative to the fixation plane). Each plane contained half of the elements. For the dynamic condition, all elements were vertically oriented and moved to the left in one plane and to the right in another plane; for the static condition, the elements were horizontally oriented in one plane and vertically oriented in another plane. Results: For the range of motion speed that we measured (from 0.17°/s to 5.33°/s), we observed clear speed tuning of the stereo sensitivity (P = 3.0 × 10-5). The shape of this tuning did not significantly change with different spatial frequencies. We also found a significant difference in stereo sensitivity between stereopsis with static and laterally moving stimuli (speed = 0.67°/s; P = 0.004). Such difference was not evident when we matched the task between the static and moving stimuli. Conclusions: We report that lateral motion modulates human global depth perception. This motion/stereo constraint is related to motion velocity not stimulus temporal frequency. We speculate that the processing of motion-based stereopsis of the kind reported here occurs in dorsal extrastriate cortex.
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Percepção de Profundidade/fisiologia , Percepção de Movimento/fisiologia , Psicofísica/métodos , Disparidade Visual/fisiologia , Visão Binocular , Córtex Visual/fisiologia , Adulto , Feminino , Humanos , Masculino , Valores de Referência , Adulto JovemRESUMO
Purpose: To determine binocular summation of surgically treated intermittent exotropia (IXT) patients by measuring the contrast threshold. Methods: We recruited 38 surgically treated IXT patients aged 8-24 years and 20 age-matched healthy controls. All participants had normal or corrected-to-normal visual acuity (Snellen ≥ 20/20) in both eyes. The IXT patients had undergone the surgery at least a year prior to the study. Twenty-one of them obtained good alignment and 17 experienced a recurrence of exotropia. We measured the observers' monocular and binocular contrast sensitivities (CS) at six spatial frequencies (1.5, 3, 6, 12, 18, 24 cycles/degree) as an index of visual information processing at the threshold level. Binocular summation was evaluated against a baseline model of simple probability summation based on the CS at each spatial frequency and the area under the log contrast sensitivity function (AULCSF). Results: The exo-deviation of IXTs with good alignment was -6.38 ± 3.61 prism diopters (pd) at 33 cm and -5.14 ± 4.07 pd at 5 m. For the patients with recurrence, it was -23.47 ± 5.53 pd and -21.12 ± 4.28 pd, respectively. There was no significant difference in the binocular summation ratio (BSR) between the surgically treated IXT patients, including those with good alignment and recurrence, and normal controls at each spatial frequency [F (2,55) = 0.416, P = 0.662] and AULCSF [F (2,55) = 0.469, P = 0.628]. In addition, the BSR was not associated with stereopsis (r = -0.151, P = 0.365). Conclusion: Our findings of normal contrast sensitivity binocular summation ratio in IXT after surgical treatment suggest that the ability of the visual cortex in processing binocular information is intact at the contrast threshold level.
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PURPOSE: The current study was to investigate whether myopia affected peripheral motion detection and whether the potential effect interacted with spatial frequency, motion speed, or eccentricity. METHODS: Seventeen young adults aged 22-26 years participated in the study. They were six low to medium myopes [spherical equivalent refractions -1.0 to -5.0 D (diopter)], five high myopes (<-5.5 D) and six emmetropes (+0.5 to -0.5 D). All myopes were corrected by self-prepared, habitual soft contact lenses. A four-alternative forced-choice task in which the subject was to determine the location of the phase-shifting Gabor from the four quadrants (superior, inferior, nasal, and temporal) of the visual field, was employed. The experiment was blocked by eccentricity (20° and 27°), spatial frequency (0.6, 1.2, 2.4, and 4.0 cycles per degree (c/d) for 20° eccentricity, and 0.6, 1.2, 2.0, and 3.2 c/d for 27° eccentricity), as well as the motion speed [2 and 6 degree per second (d/s)]. RESULTS: Mixed-model analysis of variances showed no significant difference in the thresholds of peripheral motion detection between three refractive groups at either 20° (F[2,14] = 0.145, p = 0.866) or 27° (F[2,14] = 0.475, p = 0.632). At 20°, lower motion detection thresholds were associated with higher myopia (p < 0.05) mostly for low spatial frequency and high-speed targets in the nasal and superior quadrants, and for high spatial frequency and high-speed targets in the temporal quadrant in myopic viewers. Whereas at 27°, no significant correlation was found between the spherical equivalent and the peripheral motion detection threshold under all conditions (all p > 0.1). Spatial frequency, speed, and quadrant of the visual field all showed significant effect on the peripheral motion detection threshold. CONCLUSION: There was no significant difference between the three refractive groups in peripheral motion detection. However, lower motion detection thresholds were associated with higher myopia, mostly for low spatial frequency targets, at 20° in myopic viewers.
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PURPOSE: Recently, Lunghi et al. (2016) showed that amblyopic eye's visual acuity per se after 2 months of occlusion therapy could be predicted by a homeostatic plasticity, that is, the temporary shift of perceptual eye dominance observed after a 2-h monocular deprivation, in children with anisometropic amblyopia. In this study, we assess whether the visual acuity improvement of the amblyopic eye measured after 2 months of occlusion therapy could be predicted by this plasticity. METHODS: Seven children (6.86 ± 1.46 years old; SD) with anisometropic amblyopia participated in this study. All patients were newly diagnosed and had no treatment history before participating in our study. They finished 2 months of refractive adaptation and then received a 4-h daily fellow eye patching therapy with an opaque patch for a 2-month period. Best-corrected visual acuity of the amblyopic eye was measured before and after the patching therapy. The homeostatic plasticity was assessed by measuring the temporary shift of perceptual eye dominance from 2-h occlusion of the amblyopic eye before treatment. A binocular phase combination paradigm was used for this study. RESULTS: We found that there was no significant correlation between the temporary shift of perceptual eye dominance observed after 2-h occlusion of the amblyopic eye and the improvement in visual acuity in the amblyopic eye from 2 months of classical patching therapy. This result, although in disagreements with the conclusions of Lunghi et al. involving the short-term patching of the amblyopic eye, is in fact consistent with a reanalysis of Lunghi and colleagues' data. CONCLUSION: The short-term changes in perceptual eye dominance as a result of short-term monocular deprivation do not provide an index of cortical plasticity in the general sense such that they are able to predict acuity outcomes from longer-term classical patching.
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Purpose: To assess interocular delays in amblyopes with stereopsis and to evaluate the relationship between interocular delays and the clinical characteristics. Methods: Twenty amblyopes with stereopsis (median, 400 arcseconds) and 20 controls with normal or corrected to normal visual acuity (≤0 logMAR) and normal stereopsis (≤60 arcseconds) participated. Using a rotating cylinder defined by horizontally moving Gabor patches, we produced a spontaneous Pulfrich phenomenon in order to determine the interocular delays, that is, the interocular phase difference at which ambiguous motion in plane was perceived. Two spatial frequencies-a low (0.95 cycles/degree [c/d]) and a medium (2.85 c/d) spatial frequency-were tested. Results: The absolute interocular delays of the amblyopic group was significantly longer than that of the controls at both low or medium spatial frequencies (P < 0.01). However, the interocular delays was not always in favor of the fellow eye: 35% of the amblyopes (7/20) showed a faster processing of the amblyopic eye than that of the fellow eye at 0.95 c/d and 29.5% (5/17) at 2.85 c/d. No significant correlation was found between interocular delays and the clinical characteristics (e.g., age, treatment history, stereoacuity, and magnitude of anisometropia) in this amblyopic cohort. Conclusions: The interocular delays in amblyopes with stereopsis might result from either a faster or slower processing of the amblyopic eye relative to the fellow eye. This work provides important additional information for binocular processing of dynamic visual stimuli in amblyopia. However, the special role between this form of interocular delays and patients' clinical characteristics remains unknown.
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Ambliopia/fisiopatologia , Percepção de Profundidade/fisiologia , Percepção de Movimento/fisiologia , Transtornos da Percepção/fisiopatologia , Adulto , Feminino , Humanos , Masculino , Limiar Sensorial , Visão Binocular/fisiologia , Acuidade Visual/fisiologia , Adulto JovemRESUMO
PURPOSE: To determine if benefits from occlusion therapy are due to decreased suppression from the fellow eye in children with amblyopia. METHODS: Ten newly diagnosed amblyopes (7.2 ± 1.4 years old), two with strabismus and eight with anisometropia, participated. Patients were first given a 2-month period of refractive adaptation, followed by occlusion therapy (i.e., patching their fellow eye with an opaque patch for 4 h/day). Visual acuity of the amblyopic eye and interocular suppression were measured before and after 0.5, 1, 2, 4, and 6 months of occlusion therapy. We quantified interocular suppression with a binocular phase combination task. RESULTS: Visual acuity (in logMAR) improved from 0.50 ± 0.22 (mean ± SD) to 0.33 ± 0.20 for patients who finished a short-term (2 months) occlusion (A1-A10), from 0.53 ± 0.20 to 0.32 ± 0.22 for patients who finished a medium-term (4 months) occlusion (A1-A9), and from 0.48 ± 0.19 to 0.22 ± 0.10 for patients who finished a long-term (6 months) occlusion (A1-A8). Although their visual acuity significantly improved, their degree of suppression, which was abnormal in all cases, did not change consistently. This was true in all durations of occlusion therapy. CONCLUSION: Reduced suppression from the fixing eye might not be result from occlusion therapy.